Abstract
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A mechanism achieved with multiple CPU Core or Hyperthreading(Parallelism (并行性)) or quick Context Switch(Concurrency (并发)) or both
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Doesn’t offer true Parallelism (并行性) on Single-Core CPU which only supports one Process (进程) running at a time
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Thread-switching time is reduced to nanosecond compared to process-switching
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To users, CPU Speed is divided by the total number of Thread executing at the same time when multiple Thread sharing the same CPU Core
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Performance is a fine balance between performance gains from each Thread and Overhead of Creating Thread
Caution
- When there is a shared resource, we are likely to Race Condition (竞态条件) and Deadlock (死锁)
- Overhead of creating Thread can be significant when we are having a lot, more threads means more Context Switch
Improved Responsiveness
Can continue to run other Thread while waiting for I/O operations to complete
Run other Thread while one Thread is waiting
Improved Performance
Huge amount of performance gain is guaranteed when tasks are stateless, independent of each other & long waiting time incurs in the task
Thread Safety (线程安全)
- A piece of code that functions correctly when there is simultaneous execution of multiple Thread, adn all of them accessing the same shared resource
- Free of Race Condition (竞态条件) and Deadlock (死锁) etc